1. Field of the Invention
The present invention relates to methods of producing pyrrolidine derivatives. The purpose of the invention is to provide simple and efficient industrial production of pyrrolidine derivatives such as epoxypyrrolidines, pyrrolidinols, and the like. These pyrrolidine derivatives are important and useful synthetic intermediates for pharmaceuticals, and can be transformed to several kinds of pyrrolidine derivatives.
2. Description of the Prior Art
There are a few examples of forming 3,4-epoxypyrrolidines having formula (2) by epoxidizing the Cxe2x95x90C double bond in 3-pyrrolines having formula (3). U.S. Pat. No. 3,657,274 discloses the use of trifluoroperacetic acid; Tetrahedron Letters 36, 1621 (1995) and Tetrahedron Letters 39, 8885 (1998), J. Org. Chem. 60, 398 (1995) disclose the use of m-CPBA (m-chloroperbenzoic acid) and Tetrahedron Letters 37, 3255 (1996) discloses the use of dioxiranes. All of these methods have the following problems: (1) highly dangerous peroxides are used in the reaction, (2) the processes of producing these peroxides are very complex and involve reagents which are hard to use in the industrial methods (e.g. 90% H2O2), (3) in the group at the 1-position of 3-pyrrolines having formula (3), R1, is limited to the less basic compounds (such as amides, carbamates, and sulfamides) than ordinary cyclic amines (such as t-butoxycarbonyl (Boc), benzyloxycarbonyl (Cbz), p-toluenesulfonyl (Ts), and benzoyl (Bz) groups). This is why by-products of 3-pyrroline N-oxides are obtained selectively from ordinary cyclic amines with alkyl, aryl, and/or aralkyl groups at the 1-position of 3-pyrrolines.
On the other hand, there are a few examples in which epoxidation of basic 3-pyrrolines is disclosed. U.S. Pat. No. 4,230,718 discloses the formation of 3,4-epoxypyrrolidines via chlorohydrins, from 3-pyrrolines using aqueous HCl and Cl2 gas. Epoxidation of 3-pyrrolines using CH3CN and H2O2 is disclosed in J. Org. Chem. 47, 5196 (1982), and J. Chem. Soc., Chem. Commun. 293 (1995) discloses the use of BF3/OEt2. Unfortunately, 3,4-dichloropyrrolidine by-products are formed in U.S. Pat. No. 4,230,718, and pyrrole by-products are formed in J. Org. Chem. 47, 5196 (1982). In the case of J. Chem. Soc., Chem. Commun. 293 (1995), both BF3/OEt2 and dioxiranes are expensive and are difficult to use from the point of industrialization.
Therefore, these kinds of the oxidation reactions without limitation of substituents on nitrogen, and without production of by-products are unknown. Needless to say, nothing in the above reactions is useful for persulfates to be accelerated by irradiation.
Examples of the synthesis of 3-pyrrolidinols having formula (1) from 3,4-epoxypyrrolidines having formula (2) are found in Tetrahedron Letters 35, 7099 (1994), Tetrahedron Letters 39, 8885 (1998), J. Org. Chem 47, 5196 (1982), J. Org. Chem 60, 398 (1995) (by hydrolysis), and in U.S. Pat. No. 4,254,135 and German Patent No. 3,906,365 (by alcoholysis and aminolysis). These methods have the following disadvantages: (1) the synthesized 3,4-epoxypyrrolidines must be subjected to several isolation processes including distillation, crystallization, etc. to derivatize 3-pyrrolidinols, (2) total yields are low, (3) operation is inconvenient and costs are high.
(4) There is no known one-pot synthesis of 3-pyrrolidinols having formula (1) from 3-pyrrolines having formula (3).
One-pot synthesis of 3,4-dihydroxypyrrolidines from 3-pyrroline compounds is disclosed by J. Org. Chem. 60, 398 (1995), Tetrahedron Letters 35, 7099 (1998), and Tetrahedron Letters 28, 535 (1987) in which N-methylmorpholine N-oxides are used in the presence of osmium tetroxide (OsO4) or potassium permanganate (KMnO4). However, these methods have the following problems: (1) they are only available for the synthesis of cis-3,4-dihydroxypyrrolidines, (2) waste liquid, including oxidizing reagents of osmium tetroxide (OsO4) and potassium permanganate (KMnO4) can cause problems under certain circumstances.
There are a few examples of the synthesis of 3-pyrrolines having formula (3) with cyclization between cis-2-butene derivatives having formula (7) and primary amines having formula (8). In U.S. Pat. No. 3,657,274 cis-1,4-dichloro-2-butene (R8xe2x95x90R9=H; A1xe2x95x90A2=Cl) is used as a starting material. In Syn. Commun. 20, 227 (1990), cis-2-butene-1,4-diol dimethanesulfonylate (R8xe2x95x90R9=H, A1xe2x95x90A2=OSO2CH3) is used as starting material. These methods have the following problems: (1) cis-1,4-dichloro-2-butene (R8xe2x95x90R9=H; A1xe2x95x90A2=Cl) is not only hard to produce industrially at low cost, but it is also a carcinogen, (2) cis-2-butene-1,4-diol dimethanesulfonylate (R8xe2x95x90R9=H; A1xe2x95x90A2=OSO2CH3) is unstable in the air and decomposes metals.
The present invention provides a novel method of preparing pyrrolidine derivatives such as 3,4-epoxypyrrolidines, 3-pyrrolidinols, and the like, in a novel, simple and efficient procedure.
The invention provides a one-pot synthesis of pyrrolidine derivatives such as 3,4-epoxypyrrolidines, 3-pyrrolidinols from 3-pyrrolines by oxidation with a peroxide in the presence of an acid. These pyrrolidine compounds are important and useful synthetic intermediates for synthesis of pharmaceuticals, and can be transformed into several kinds of pyrrolidine derivatives.
The invention provides a method for preparing pyrrolidine derivatives such as 3,4-epoxypyrrolidines, 3-pyrrolidinols and the like, by reacting 3-pyrrolines with at least one peroxide in the presence of at least one acid. Oxidation of the 3-pyrrolines having formula (3) may be accelerated using ultraviolet irradiation, if desired.
The 3-pyrrolidinols are of formula (1): 
wherein R1 is hydrogen (H), a halogen, a cyano group (CN), a nitro group (NO2), a hydroxyl group (OH), an alkoxyl group (OR), a carboxyl group (CO2H), an alkoxycarbonyl group (CO2R), an acyl group (COR), a carbamoyl group (H2NCO), a sulfide group (SH, or SR), a sulfinyl group (SOR), a sulfonyl group (SO2R), a sulfamide group (SO2NRRxe2x80x2), or a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted, R2 and R3 represent a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted, and Nu is a hydroxyl group (OH), an alkoxyl group (OR), or an amino group (NRRxe2x80x2) which can be optionally substituted. Optionally, there may be functional groups on the nitrogen atom and/or pyrrolidine ring.
The 3-pyrrolidinols include, but are not limited to, 3,4-dihydroxypyrrolidines, such as 3,4-dihydroxypyrrolidine, 1-methyl-3,4-dihydroxypyrrolidine, 1-cyclohexyl-3,4-dihydroxypyrrolidine, 1-benzyl-3,4-dihydroxypyrrolidine, 1-phenyl-3,4-dihydroxypyrrolidine, 2-[3-chloro-4-(3,4-dihydroxypyrrolidin-1-yl)phenyl]propionic acid, methyl 2-[3-chloro-4-dihydroxypyrrolidin-1-yl)phenyl]propionate, and the like.
Specific examples of 3-pyrrolidinols include, but are not limited to, 4-amino-3-pyrrolidinols such as 4-amino-3-pyrrolidinol, 1-methyl-4-amino-3-pyrrolidinol, 1-cyclohexyl-4-amino-3-pyrrolidinol, 1-benzyl-4-amino-3-pyrrolidinol, 1-phenyl-4-amino-3-pyrrolidinol, 2-[3-chloro-4-(4-amino-3-hydroxypyrrolidin-1-yl)phenyl]propionic acid, methyl 2-[3-chloro-4-(4-amino-3-hydroxypyrrolidin-1-yl)phenyl]propionate; 4-benzylamino-3-pyrrolidinols such as 4-benzylamino-3-pyrrolidinol, 1-methyl-4-benzylamino-3-pyrrolidinol, 1-cyclohexyl-4-benzylamino-3-pyrrolidinol, 1-benzyl-4-benzylamino-3-pyrrolidinol, 1-phenyl-4-benzylamino-3-pyrrolidinol, 2-[3-chloro-4-(4-benzylamino-3-hydroxypyrrolidin-1-yl)phenyl]propionic acid, methyl 2-[3-chloro-4-(4-benzylamino-3-hydroxypyrrolidin-1-yl)phenyl]propionate, and the like; 4-alkoxy-3-pyrrolidinols such as 4-methoxy-3-pyrrolidinol, 1-methyl-4-methoxy-3-pyrrolidinol, 1-cyclohexyl-4-methoxy-3-pyrrolidinol, 1-benzyl-4-methoxy-3-pyrrolidinol, 1-phenyl-4-methoxy-3-pyrrolidinol, 2-[3-chloro-4-(4-methoxy-3-hydroxypyrrolidin-1-yl)phenyl]propionic acid, methyl 2-[3-chloro-4-(4-methoxy-3-hydroxypyrrolidin-1-yl)phenyl]propionate, and the like.
The 3,4-epoxypyrrolidines are of the formula (2): 
wherein R1 is hydrogen (H), a halogen, a cyano group (CN), a nitro group (NO2), a hydroxyl group (OH), an alkoxyl group (OR), a carboxyl group (CO2H), an alkoxycarbonyl group (CO2R), an acyl group (COR), a carbamoyl group (H2NCO), a sulfide group (SH, or SR), a sulfinyl group (SOR), a sulfonyl group (SO2R), a sulfamide group (SO2NRRxe2x80x2), or a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted; R2 and R3 each represent a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted. Optionally, there may be functional groups on the nitrogen atom and/or pyrrolidine ring.
The 3,4-epoxypyrrolidines include, but are not limited to 3,4-epoxypyrrolidine, 1-methyl-3,4-epoxypyrrolidine, 1-cyclohexyl-3,4-epoxypyrrolidine, 1-benzyl-3,4-epoxypyrrolidine, 1-phenyl-3,4-epoxypyrrolidine, 2-[3-chloro-4-(3,4-epoxypyrrolidin-1-yl)phenyl]propionic acid, methyl 2-[3-chloro-4-(3,4-epoxypyrrolidin-1-yl)phenyl]propionate, and the like.
The 3-pyrrolines are of formula (3): 
wherein R1 is hydrogen (H), a halogen, a cyano group (CN), a nitro group (NO2), a hydroxyl group (OH), an alkoxyl group (OR), a carboxyl group (CO2H), an alkoxycarbonyl group (CO2R), an acyl group (COR), a carbamoyl group (H2NCO), a sulfide group (SH, or SR), a sulfinyl group (SOR), a sulfonyl group (SO2R), a sulfamide group (SO2NRRxe2x80x2), or a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted; R2 and R3 each represent a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted. Optionally, there may be functional groups on the nitrogen atom and/or pyrrolidine ring. The 3-pyrrolines include, but are not limited to 3-pyrroline, 1-methyl-3-pyrroline, 1-ethyl-3-pyrroline, 1-propyl-3-pyrroline, 1-cyclohexyl-3-pyrroline, 1-trichloromethyl-3-pyrroline, 1-phenyl-3-pyrroline, 1-tolyl-3-pyrroline, 1-benzyl-3-pyrroline, 2-[3-chloro-4-(3-pyrrolin-1-yl)phenyl]propionic acid, methyl 2-[3-chloro-4-(3-pyrrolin-1-yl)phenyl]propionate, and the like. Of these compounds, 3-pyrroline, 1-benzyl-3-pyrroline, 1-cyclohexyl-3-pyrroline are preferred. Most preferred are 1-benzyl-3-pyrroline and 1-cyclohexyl-3-pyrroline.
Preferable acids in the oxidation process of 3-pyrrolines are compounds whose formula contains a sulfur atom (S), such as sulfuric acid or sulfonic acids having formula (11). Formula (11) is represented by:
R14SO3Hxe2x80x83xe2x80x83(11)
wherein R14 represents a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group which can be optionally substituted by a halogen, a cyano group (CN), a nitro group (NO2), a hydroxyl group (OH), an alkoxyl group (OR), a silyl group (SiR3), a carboxyl group (CO2H), an alkoxycarbonyl group (CO2R), and/or an acyl group (COR).
These sulfonic acids having formula (11) can be classified under four sulfonic acids: alkylsulfonic acids, cycloalkylsulfonic acids, arylsulfonic acids, and aralkylsulfonic acids. Suitable alkylsulfonic acids include, but are not limited to methanesulfonic acids, trifluoromethanesulfonic acids, trichloromethanesulfonic acids, ethanesulfonic acids, and the like. Suitable cycloalkylsulfonic acids include, but are not limited to, cyclopropanesulfonic acids, cyclohexanesulfonic acids, and the like. Suitable arylsulfonic acids include, but are not limited to, benzenesulfonic acids, o-, m-, p-fluorobenzenesulfonic acids, o-, m-, p-chlorobenzenesulfonic acids, o-, m-, p-nitrobenzenesulfonic acids, o-, m-, p-cyanobenzenesulfonic acids, o-, m-, p-toluenesulfonic acids, mesitylenesulfonic acids, naphthalenesulfonic acids, and the like. Suitable aralkylsulfonic acids include, but are not limited to, benzylsulfonic acids, o-, m-, p-fluorobenzylsulfonic acids, o-, m-, p-chlorobenzylsulfonic acids, o-, m-, p-nitrobenzylsulfonic acids, o-, m-, p-cyanobenzylsulfonic acids, and the like.
Of these compounds, sulfuric acid, methanesulfonic acids, benzenesulfonic acids, p-chlorobenzenesulfonic acids are preferred. In particular, sulfuric acid is most preferably used.
The preferable amount of acid used is in the range of about 1.0-3.0 mole acid to about 1.0 moles 3-pyrrolines having formula (3) can be used efficiently and economically. Peroxides used in the oxidation of the 3-pyrrolines of formula (3) may be peroxymonosulfuric acids, or their salts (peroxymonosulfates) having formula (4), peroxydisulfuric acids, or their salts (peroxydisulfates) having formula (5). Formula (4) is represented by:
MxHy(SO5)zxe2x80x83xe2x80x83(4)
wherein M is an alkali metal (1A in the periodic table), an alkaline earth metal (2A in the periodic table), an element from 3A in the periodic table, or an ammonium group having formula (6), and each of x, y, and z can be represented numerically (0-3) provided the relation x+y=2z is satisfied. Formula (5) is represented by:
MxHy(S2O8)zxe2x80x83xe2x80x83(5)
where M is an alkali metal (1A in the periodic table), an alkaline earth metal (2A in the periodic table), an element from 3A in the periodic table, or an ammonium group having formula (6), and each of x, y, and z can be represented numerically (0-3) provided the relation x+y=2z is satisfied. Formula (6) is represented by: 
wherein R4-R7 represent hydrogen, a C1-C20 alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group. Peroxymonosulfuric acid, salts (peroxymonosulfates) or peroxydisulfuric acid, salts (peroxydisulfates) are preferable.
Metal peroxymonosulfates include, but are not limited to, sodium peroxymonosulfate (Na2SO5), potassium peroxymonosulfate (K2SO5), barium peroxymonosulfate (BaSO5), rubidium peroxymonosulfate (RbSO5), and the like.
Metal peroxyhydrogenmonosulfates include, but are not limited to, sodium peroxyhydrogenmonosulfate (NaHSO5), potassium peroxyhydrogenmonosulfate (KHSO5), and the like.
Ammonium peroxymonosulfates include, but are not limited to, ammonium peroxymonosulfate ((NH4)2SO5), tetramethylammonium peroxymonosulfate ((Me4N)2SO5), tetraethylammonium peroxymonosulfate ((Et4N)2SO5), tetrapropylammonium peroxymonosulfate ((Pr4N)2SO5), tetrabutylammonium peroxymonosulfate ((Bu4N)2SO5), tetrahexylammonium peroxymonosulfate, tetradecylammonium peroxymonosulfate, tetralaurylammonium peroxymonosulfate, tetrabenzylammonium peroxymonosulfate ((Bn4N2SO5), benzyltrimethylammonium peroxymonosulfate ((BnMe3N)2SO5), benzyltriethylammonium peroxymonosulfate ((BnEt3N)2SO5), benzyltributylammonium peroxymonosulfate ((BnBu3N)2SO5), lauryltrimethylammonium peroxymonosulfate, lauryltriethylammonium peroxymonosulfate, and the like.
Ammonium peroxyhydrogenmonosulfates include, but are not limited to, ammonium peroxyhydrogenmonosulfate ((NH4)HSO5), tetramethylammonium peroxyhydrogenmonosulfate ((Me4N)HSO5), tetraethylammonium peroxyhydrogenmonosulfate ((Et4N)HSO5), tetrapropylammonium peroxyhydrogenmonosulfate ((Pr4N)HSO5), tetrabutylammonium peroxyhydrogenmonosulfate ((Bu4N)HSO5), tetrahexylammonium peroxyhydrogenmonosulfate, tetradecylammonium peroxyhydrogenmonosulfate, tetralaurylammonium peroxyhydrogenmonosulfate, tetrabenzylammonium peroxyhydrogenmonosulfate (Bn4N)HSO5), benzyltrimethylammonium peroxyhydrogenmonosulfate ((BnMe3N)HSO5), benzyltriethylammonium peroxyhydrogenmonosulfate ((BnEt3N)HSO5), benzyltributylammonium peroxyhydrogenmonosulfate ((BnBu3N)HSO5), lauryltrimethylammonium peroxyhydrogenmonosulfate, lauryltriethylammonium peroxyhydrogenmonosulfate, and the like.
Metal peroxydisulfates include, but are not limited to, sodium peroxydisulfate (Na2S2O8), potassium peroxydisulfate (K2S2O8), barium peroxydisulfate (BaS2O8), rubidium peroxydisulfate (RbS2O8), and the like.
Metal peroxyhydrogendisulfates include, but are not limited to, sodium peroxyhydrogendisulfate (NaHS2O8), potassium peroxyhydrogendisulfate (KHS2O8), and the like.
Ammonium peroxydisulfates include, but are not limited to, ammonium peroxydisulfate ((NH4)2S2O8), tetramethylammonium peroxydisulfate ((Me4N)2S2O8), tetraethylammonium peroxydisulfate ((Et4N)2S2O8), tetrapropylammonium peroxydisulfate ((Pr4N)2S2O8), tetrabutylammonium peroxydisulfate ((Bu4N)2S2O8), tetrahexylammonium peroxydisulfate, tetradecylammonium peroxydisulfate, tetralaurylammonium peroxydisulfate, tetrabenzylammonium peroxydisulfate ((Bn4N2S2O8), benzyltrimethylammonium peroxydisulfate ((BnMe3N2SO5), benzyltriethylammonium peroxydisulfate ((BnEt3N)2S2O8), benzyltributylammonium peroxydisulfate ((BnBu3N)2S2O8), lauryltrimethylammonium peroxydisulfate, lauryltriethylammonium peroxydisulfate, and the like.
Ammonium peroxyhydrogendisulfates include, but are not limited to, ammonium peroxyhydrogendisulfate ((NH4)HS2O8), tetramethylammonium peroxyhydrogendisulfate ((Me4N)HS2O8), tetraethylammonium peroxyhydrogendisulfate ((Et4N)HS2O8), tetrapropylammonium peroxyhydrogendisulfate ((Pr4N)HS2O8), tetrabutylammonium peroxyhydrogendisulfate ((Bu4N)HS2O8), tetrahexylammonium peroxyhydrogendisulfate, tetradecylammonium peroxyhydrogendisulfate, tetralaurylammonium peroxyhydrogendisulfate, tetrabenzylammonium peroxyhydrogendisulfate ((Bn4N)HS2O8), benzyltrimethylammonium peroxyhydrogendisulfate ((BnMe3N)HS2O8), benzyltriethylammonium peroxyhydrogendisulfate ((BnEt3N)HS2O8), benzyltributylammonium peroxyhydrogendisulfate ((BnBu3N)HS2O8), lauryltrimethylammonium peroxyhydrogendisulfate, lauryltriethylammonium peroxyhydrogendisulfate, and the like.
The preferable peroxymonosulfate is potassium peroxyhydrogenmonosulfate (KHSO5) Sodium peroxydisulfate (Na2S2O8) and/or ammonium peroxydisulfate ((NH4)2S2O8) are the preferred peroxydisulfates. The oxidation can be performed either with peroxysulfates alone or with a peroxysulfate mixture. For example, suitable peroxides include OXONE (produced by DuPont), which is a mixture of KHSO5/KHSO4/K2SO4=2/1/1, stabilized by mixing inorganic compounds deactivated for explosion. Suitable amounts of peroxides are in the range of about 1.0-2.0 moles of peroxides to 1.0 mole of 3-pyrrolines having formula (3) and can be preferably used efficiently and economically.
The substituent group Nu in formula (1) derives from nucleophiles of water, alcohols, amines, and the like. Alcohols include, but are not limited to, methanol (MeOH), ethanol (EtOH), propanol (PrOH), butanol (BuOH), hexanol, cyclohexanol, phenol (PhOH), chlorophenol, dichlorophenol, trichlorophenol, catechol, ethylene glycol, diethylene glycol, and the like.
Amines include, but are not limited to, ammonia (NH3), methylamine (MeNH2), ethylamine (EtNH2), propylamine (PrNH2), butylamine (BuNH2), cyclohexylamine, allylamine, homoallylamine, benzylamine (BnNH2), aniline (PhNH2), chloroaniline, bromoaniline, o-, m-, p-toluidine, dimethylamine (Me2NH), diethylamine (Et2NH), dipropylamine (Pr2NH), dibutylamine (Bu2NH), dicyclohexylamine, diallylamine, bis(homoallyl)amine, dibenzylamine (Bn2NH), N-methylaniline, N-methylchloroaniline, N-methylbromoaniline, benzylmethylamine (BnMeNH), and the like. Preferable nucleophiles include water, methanol, ethanol, ammonia, allylamine, cyclohexylamine, and benzylamine.
These nucleophiles can be added to the solution either before or after oxidation, so that the one-pot procedure may proceed continuously without isolating the intermediates to obtain the corresponding products, 3-pyrrolidinols. In the case of preparing 3,4-epoxypyrrolidines having formula (2), these nucleophiles are not necessary, and can be used as inactive solvents by controlling the reaction temperature.
If desired, the oxidation of 3-pyrrolines having formula (3) may be accelerated using ultraviolet light. Lamps with wave length from the ultraviolet to the visible light range (200 nm-400 nm) can be selected for the irradiation of 3-pyrrolines. For example, such lamps include an Argon Resonance Lamp, a Flash UV (Ultra Violet) Lamp, an Ultra High Pressure Hg (mercury) Lamp, a High Pressure Hg (mercury) Lamp, a Low Pressure Hg (mercury) Lamp, a Deuterium Lamp, a Xe (xenon) Lamp, a W (tungsten) Lamp, a Metal Halide Lamp, and the like. In particular, a High Pressure Hg (mercury) Lamp and a Xe (xenon) Lamp are preferable.
Although the use of these lamps is able to accelerate oxidation of 3-pyrrolines having formula (3), the reaction system can be changed freely by changing the irradiation time, the irradiation strength or by omitting the irradiation.
The reaction solvents may be freely selected in the oxidation process. For example, suitable reaction solvents include, but are not limited to, water, methanol, ethanol, propanol, acetone, methylethylketone, methylisobutylketone, ethyl acetate, methyl propionate, hexane, cyclohexane, benzene, toluene, chloroform, dichloromethane, dichloroethane, tetrahydrofuran, diethyl ether, diisopropyl ether, ethylene glycol, diethylene glycol, and the like. Either only one kind of solvent may be used, or mixtures of solvents may be used. Alternatively, the solvents can be omitted. With regard to combining the above solvents with the nucleophiles from which substituent group Nu in formula (1) derives, they can be made active and/or inactive by controlling the reaction temperature.
The reaction temperature will depend on the time required for completing the oxidation. In general, the reaction may be conducted at about 0-100xc2x0 C. In particular, the reaction temperature is about 0-30xc2x0 C. for obtaining 3,4-epoxypyrrolidines and is about 30-100xc2x0 C. for obtaining 3-pyrrolidinols.
3-pyrrolines having formula (3) may be produced by reacting cis-2-butene derivatives having formula (7) with at least one primary amine having formula (8). This reaction allows cyclization of cis-2-butene derivatives of formula (7) and the formation of 3-pyrrolines of formula (3). Cis-2-butene derivatives of formula (7) may be produced from cis-2-butene-1,4-diols of formula (9) by reacting the cis-2-butene-1,4-diols of formula (9) with a halogenation reagent in the presence of at least one base.
The substituent groups R10 in the primary amines of formula (8):
R10xe2x80x94NH2xe2x80x83xe2x80x83(8)
which are used for preparing 3-pyrrolines, include, but are not limited to, alkyl groups, such as methyl, ethyl, n-, iso-propyl, n-, i-, t-butyl, trifluoromethyl, and the like; cycloalkyl groups, such as cyclohexyl and the like; alkenyl groups, such as vinyl, allyl, methallyl, homoallyl, and the like; aryl groups, such as phenyl, fluorophenyl, difluorophenyl, trifluorophenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, nitrophenyl, dinitrophenyl, trinitrophenyl, cyanophenyl, dicyanophenyl, tricyanophenyl, tolyl, dimethylphenyl, trimethylphenyl, trifluoromethylphenyl, naphthyl, and the like; and aralkyl groups, such as benzyl, phenylethyl, phenethyl, naphthylmethyl, 1-, 2-phenylvinyl, and the like.
Primary amines include, but are not limited to, methylamine, ethylamine, n-, i-propylamine, n-, i-, t-butylamine, cyclohexylamine, allylamine, allylamine, homoallylamine, benzylamine, aniline, chloroaniline, bromoaniline, toluidine and the like. Of the suitable primary amines, cyclohexylamine, benzylamine, and aniline are preferable. Suitable amounts of amines are in the range of about 3.0-5.0 moles amines to 1.0 mole of cis-2-butene derivatives having formula (7) and can be preferably used efficiently and economically.
Bases used for preparing cis-2-butene derivatives of formula (7) from cis-2-butene-1,4-diols of formula (9), can be selected freely unless these would react with the starting materials. Formula (7) is represented by: 
wherein R8 and R9 are independently hydrogen (H) or a C1-C10 alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group which can be optionally substituted, A1 and A2 are independently halogens or sulfonyloxy groups. Formula (9) is represented by: 
wherein R11 and R12 are independently hydrogen (H) or a C1-C10 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group which can be optionally substituted. Tertiary amines are the preferred bases. Tertiary amines include, but are not limited to, triethylamine, tripropylamine, tributylamine, tribenzylamine, N, Nxe2x80x2-dimethylaniline, N, Nxe2x80x2-dimethyltoluidine, pyridine, 4-(N, Nxe2x80x2-dimethylamino)pyridine, and the like. Preferably, the amount of bases used is in the range of about 2.0-3.0 moles of base to 1.0 mole of cis-2-butene-1,4-diols of formula (9). More preferably the amount of base used is in the range of about 2.0-2.2 moles of base and can be used efficiently and economically.
The substituent group, A3, in the sulfonyl halides of formula (10) which are used as halogenation reagents in the first process include halogens such as Cl, Br, and I. Formula (10) is represented by:
R13SO2A3xe2x80x83xe2x80x83(10)
wherein R13 represents a C1-C10 alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group optionally substituted; and A3 is a halogen. In particular, sulfonyl chlorides are preferable.
The substituent groups R13 in the sulfonyl halides, which are used for preparing cis-2-butene derivatives of formula (7) or 3-pyrrolines of formula (3), include, but are not limited to alkyl groups, such as methyl, ethyl, n-, iso-propyl, n-, i-, t-butyl, trifluoromethyl, and the like; cycloalkyl groups, such as cyclohexyl and the like; alkenyl groups, such as vinyl, allyl, methallyl, homoallyl, and the like; aryl groups, such as phenyl, fluorophenyl, difluorophenyl, trifluorophenyl, chlorophenyl, dichlorophenyl, trichlorophenyl, bromophenyl, dibromophenyl, tribromophenyl, nitrophenyl, dinitrophenyl, trinitrophenyl, cyanophenyl, dicyanophenyl, tricyanophenyl, tolyl, dimethylphenyl, trimethylphenyl, trifluoromethylphenyl, naphthyl, and the like; and aralkyl groups, such as benzyl, phenylethyl, phenethyl, naphthylmethyl, 1-, 2-phenylvinyl, and the like.
The sulfonyl chlorides include, but are not limited to, methanesulfonyl chloride, ethanesulfonyl chloride, n-, i-propanesulfonyl chloride, n-, i-, t-butanesulfonyl chloride, cyclohexanesulfonyl chloride, trifluoromethanesulfonyl chloride, benzenesulfonyl chloride, o-, m-, p-chlorobenzenesulfonyl chloride, o-, m- p-toluenesulfonyl chloride, naphthalenesulfonyl chloride, benzylsulfonyl chloride, and the like. Of the suitable sulfonyl chlorides, methanesulfonyl chloride, benzenesulfonyl chloride, and p-toluenesulfonyl chloride are preferable.
The amount of sulfonyl halides used is in the range of about 2.0-3.0 moles of base to 1.0 mole cis-2-butene-1,4-diols of formula (9). Preferably, the amount is about 2.0-2.2 moles of sulfonyl halides is used for efficiency and economy.
In the case where the following two processes:
(A) derivation of cis-2-butene compounds from cis-2-butene-1,4-diols having formula (9) and
(B) cyclization between cis-2-butene derivatives of formula (7) and primary amines of formula (8)
are performed in a continuous process, without isolating cis-2-butene derivatives about 2.0 moles of sulfonyl halides is preferably used to prevent side reactions between excess sulfonyl halides and primary amines.
Reaction solvents may be selected freely in the preparation process of cis-2-butene derivatives or 3-pyrrolines. For example, acetone, methylethylkotone, methylisobutylketone, ethyl acetate, methyl propionate, hexane, cyclohexane, benzene, toluene, chloroform, dichloromethane, dichloroethane, carbon tetrachloride, tetrahydrofuran, diethyl ether, diisopropyl ether, and the like are suitable reaction solvents. Either one kind of solvent, mixtures thereof, or no solvents can be used.
In the case where the two processes (A) and (B) are continuously conducted without isolating cis-2-butene derivatives of formula (7), the same solvent can be used through several processes.
The temperature depends on the time for completing this cyclization reaction. Generally, the temperature is about 0 to 15xc2x0 C. when sulfonyl halides of formula (10) are added to the reaction mixture. Following addition of the sulfonyl halides, the reaction may be performed at about ambient temperature to 60xc2x0 C. with stirring of the solution. Although the temperature in the second stage depends on the reactivity of primary amines of formula (8), the temperature range may be about room temperature to about 100xc2x0 C.
With regard to the operation of reaction mixture after completion and the isolation of products, the two processes of the previous stage can be conducted to the next stage continuously without isolating intermediates. If one needs to isolate the products (intermediates), one has only to conduct simple operations such as filtration, extraction, and so on. xe2x80x9cConducting the two processes of the previous stage to the next stage continuously without isolating intermediatesxe2x80x9d refers to a one-pot reaction, advancing to the next reaction without transferring the solution to the another reactor. For example, if the cis-2-butene derivative solution contains the following compounds, 
wherein R8 and R9 are independently hydrogen (H) or a C1-C10 alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group which can be optionally substituted; R13 represents a C1-C10 alkyl group, a cycloalkyl group, an aryl group, an aralkyl group optionally substituted; and A3 is a halogen, or if the oxidation solution contains the following two compounds: 
wherein R1 is hydrogen (H), a halogen, a cyano group (CN), a nitro group (NO2), a hydroxyl group (OH), an alkoxyl group (OR), a carboxyl group (CO2H), an alkoxycarbonyl group (CO2R), an acyl group (COR), a carbomyl group (H2NCO), a sulfide group (SH, or SR), a sulfinyl group (SOR), a sulfonyl group (SO2R), a sulfamide group (SO2NRRxe2x80x2, or a C1-C10 alkyl group, cycloalkyl group, aryl group, aralkyl group, optionally substituted; R2 and R3 each independently represent a C1-C10 alkyl group, cycloalkyl group, aryl group, or aralkyl group, optionally substituted, and Nu is a hydroxyl group (OH), alkoxyl group (OR), or amino group (NRRxe2x80x2) optionally substituted, we can conduct the solution to the next stage continuously without isolating intermediates.
Processing after continuous reaction only involves simple operations such as filtration, extraction, and so on. For example, the following methods may be freely selected: (1) after direct addition and reaction of primary amines to the solution Process (A), both tertiary amine salts and primary amine salts are removed; (2) after removing tertiary amine salts from the solution Process (A), the addition and reaction of primary amines is performed followed by removal of primary amine salts.